doc: Fix another ID typo.

Dependencies

• [2] 2LTNY56W doc: Add preliminary section about `release.nix'.
• [3] PKE6I67S doc: Import the "Creating Projects" chapter by Visser & Dolstra.
• [4] W4LDVLQF doc: Show example of `configureFlags'.

Change contents

• replacement in doc/manual/projects.xml at line 195
  [2.1731]→[2.1731:1791](∅→∅)
  − { helloSrc }: <co xml:id='ex-hello-co-tarball-arg' />
  [2.1731]

  [2.1791]
  + { helloSrc }: <co xml:id='ex-hello-co-tarball-args' />